This is a Replacement Kodiak Trailer Stainless Steel disc brake Slip On rotor. Kodiak part number ROTOR-10-SS. This brake rotor is designed to slip over 5 Lug idler hubs with a 5 on 4 1/2 inch bolt pattern that have 1/2 inch studs. This slip on rotor goes over top of your hub, and then your tire and wheel goes on, and everything is tightened into place using the lug nuts. The Kodiak vented brake rotor measures 10.9 inch outside diameter. All Kodiak rotors are 100% tested and balanced. Kodiak only uses rotors that are vented to help dissipate heat faster. This rotor is for use with 14 inch or larger trailer wheels. Kodiak also offers a 6 year warranty on all their Stainless Steel parts. Get stainless steel and NEVER have to deal with rust again!